Treatment of blood



the patient in an infusion operation.

Patented Dec. 11, 1945 TREATMENT OFBLOOD Naurice M. Nesset, Glenview, Ill., assignor to Baxter Laboratories, Inc., Glenview, 111., a corporation of Delaware No Drawing, Application August 15, 1942, Serial No. 454,931

3 Claims.

This invention relates to a method for treating blood, and more particularly to a method for obtaming the bulk. of the plasma from blood in a single treatment.

An object of the invention is to provide a simpleand inexpensive method for effectively separating plasma from blood. Another object of the invention is to remove a large proportion of the plasma from blood in a relatively short time by a sed1mentation or settling method; Still another object is to provide a method for removing from blood a large proportion of the plasma therein by a simple process'requiring no refrigeration and no special apparatus.

By means of the invention, blood may be obtamed and utilized in the field, plasma being separated from the blood cells or formed elements, and the plasma being thereafter given to Simple equipment may be used, and the removal of the plasma may be carried out in a single treatment which requires only a very short time. It is not necessary to centrifuge the blood in the separation of the plasma, and no refrigeration is needed. Hemolysis of the blood is substantially eliminated, and sepsis may be readily avoided,

Another object of the invention is to obtain a relatively complete separation-of the red cells or erythrocytes in a short period of time and to obtain in the separation of the blood cells, plasma of a relatively high quality.

In the settling or sedimentation operations which have heretofore been use for. obtaining plasma from blood, a period of several days has been required for the settling of the blood cells. As a result, not only is a great deal of time consumed in the operation, but it is normally necessary to refrigerate the blood during the settling operation in order to prevent substantial hemolysis. The plasma may be obtained from blood in amore rapid operation by centrifuging the blood to separate the blood cells. Thisoperation, however, requires expensive bulky apparatus and is not entirely satisfactory for use in the field.

The present invention contemplates the mixing of the blood from which the plasma is to be obtained with a suitable compound which accelerates the settling or separation of the blood cells. In this manner, the blood cells may be substantially completely separated in a period of only a few hours by means of the settling operation. Not only is the operation economical of time, but any need for refrigeration is avoided. At the same time, it is not necessary to use expens ve or bulky apparatus in the treatment.

In accordance with the present invention, mammalian or human blood is mixed with a suit-able reagent for accelerating the sedimentation of the blood cells, and the plasma or serum is thereafter separated from the blood cells.

In the preparation of plasma human blood is ordinarily used, however, the invention is not limited to the treatment of human blood and other types of mammalian blood ma be used.

The reagent which is used for accelerating the separation of the blood cells should be one that is biologically innocuous and substantially nonanti-genic. The reagent should thus be free of any toxic body which might cause a reaction when introduced into the blood stream of the patient. At the same time, the reagent should not induce sensitivity on repeated dosage. materialis preferably one that is eliminated from the body without difliculty after being introduced into the blood stream and should exert a minimal irritating effect on living tissue.

The reagent which is mixed with the blood may be a water-dispersible polymerized organic colloidal compound, and is preferably an aliph atic compound containing carbon, hydrogen and oxygen. Preferably, the colloidal compound is one which is prepared synthetically. Methyl cellulose has been found to be particularly suitable for this purpose. Methyl cellulose and other cellulose derivatives are intended to be included in the use of the term polymer. Similarly these cellulose derivatives are to be included in referring to synthetic substances since at least the derivatives'are prepared synthetically. Another substance which has been found to be suitable is polyvinyl alcohol.

In the treatment of the blood, the accelerating agent, such as methyl cellulose, is mixed with th blood in any suitable manner. Preferably, the methyl cellulose is used in a water solution which is mixed with the'blood. When it is desired to obtain plasma rather than serum, an anti-coagulant of the conventional type for the prevention of clot formation is also mixed with the blood.

Any suitable proportion of the ingredients may be used. The anti-coagulant may be sodium citrate or sodium prosphate, or any of the other conventional anti-coagulants, and may be used in conventional quantities. The methyl cellulose is preferably used in a quantity between 0.025% and 0.2% by weight with respect to the volume of blood which is used. 0.05% of methyl cellulose has been found to be very satisfactory.

The.

The methyl cellulose is preferably of a low viscosity.

After the sedimentation accelerating reagent and the anti-coagulant are introduced into the blood, the entire mixture is thereafter agitated to obtain a thorough and complete mixture of the ingredients. The mixture may then be permitted to settle for a period of several hours. The blood cells will rapidly settle to the lower portion of the container. It has been found that the mixture may be maintained in a quiescent state for a period of between one and twelve hours for the settling operation, and that a period in the neighborhood of eight totenhours is to be preferred.

After the blood cells have settled to the lower portion of the container, the clear upper layer of plasma may be drawn oil and is ready for use.

The entire operation may be readily carried out in a closed system in order to effectively avoid sepsis.

If polyvinyl alcohol is used as the sedimentation accelerating reagent, it may be used in proportions .corresponding rather closely to those i of methyl cellulose which have been found to be suitable. Preferably, the polyvinyl alcohol which -is used is substax'itiallywater-soluble and is of relatively low viscosity.

It has been found that by adding the sedimentationaccelerating reagent to the blood, the red cells or erythrocytes settle very rapidly from the fluid portion of the blood and are very easily separated therefrom. If desired, the mixture may be subjected to centrifugation to remove the blood cells from the blood.

Although the invention has been described in connection with specific embodiments, it will be understood that many modifications and changes may be made without departing from the spirit and scope of the invention.

The sedimentation process using any biologically incecuous colloidal gummy sedimentation accelerating reagent is claimed in my copending application Serial No. 455,873, filed August 24, 1942.

I claim:

1. a method for obtaining the =-bulk of the,

plasma from blood in a single treatment, comprising mixing untreated blood with an anticoagulant and a minor-proportion of methyl cellulose, thoroughly distributing the anti-coagulant and the methyl cellulose throughout the blood, maintaining the mixture in a quiescent state for a period of time sufliciently long to permit settling of the blood cells and the formation of separate layers of plasma and blood cells and thereafter separating the plasma from the blood cells.

2. A method for obtaining the bulk of the plasma from blood in a single treatment, com

prising mixing untreated blood with an anti-coagulant and with a minor proportion of a solution of methyl cellulose, the solution containing between 0.025% and 0.2% by weight of methyl cellulose with respect to the volume of blood,

thoroughly distributing the"anti-coagulant and methyl cellulose throughout the blood, maintaining the mixture in a quiescent state for a period of time sufliciently long to permit settling of the blood cells and the formation of separate layers of plasma and blood cells and separating the plasma from the blood cells. V

3. A method for obtaining the bulk of the plasma fromblood in a single treatment, comprising mixing the untreated blood with an anticoagulant and with approximately 0.05% of low viscosity methyl cellulose in water solution, the

proportion being by weight with respect to the volume of blood, thoroughly distributing the anti-coagulant and methyl cellulose throughout the blood, maintaining the mixture in a quiescent state for a period of time sufliciently long to permit settling of the blood cells and the formation of separate layers of plasma and blood cells maintaining the mixture in a quiescent state for a period of between one hour and twelve hours to permit the settling of the blood cells,

and separating the upper layer of plasma and the lower layer of blood cells. a

NAURICE M. NESSE'I. 

